Are items actively removed from working memory during free time in children with developmental language disorder?

Abstract

Background: Children with developmental language disorder (DLD) have deficits in verbal and non-verbal processing relative to typically developing (TD) peers, potentially reflecting difficulties in working memory, processing speed and inhibition of interference. We examined working memory in children with DLD using the serial-order-in-a-box-complex span (SOB-CS) interferencebased model, which posits a time-based mechanism, free time, that governs how interference affects processing performance. Aims:(1) To determine the degree to which children with DLD and TD children differ in the amount of free time available during working memory tasks, and whether potential group differences in free time differ depending on the domain of task demands? (2) To determine the relationship between free time and interference effects on working memory accuracy in children with DLD relative to TD peers. Methods & Procedures:We examined the relationship between free time and working memory in children aged 9-13 years with DLD relative to age-matched TD peers. Working memory tasks involved five conditions that varied verbal versus non-verbal task demands in an interference processing phase relative to a recall test phase. Free time was the time between response on the interference processing task and onset of the recall test phase.Outcomes & Results: DLD and TD groups did not differ in total free time in any condition. Results indicated group differences in the relationship between free time and accuracy in the conditions involving verbal recall, but not non-verbal recall. In the verbal-only condition, relatively more free time was associated with worse accuracy for the DLD group, but with better accuracy for the TD group. In the condition with verbal recall paired with non-verbal interference processing, relatively more free time was associated with better accuracy for the DLD group, but not for the TD group. Conclusions & Implications:The overall findings suggest that free time between cognitive operations is positively associated with working memory for both verbal and non-verbal recall, except in the presence of high verbal interference for the DLD group (i.e., verbal interference paired with verbal recall). This